Structure for protecting sea and/or river construction work, and protective block used

ABSTRACT

The invention relates to a structure for protecting sea and/or river construction work, which uses blocks ( 1 ) including a central core ( 2 ) having an upper portion ( 4 ) and a lower portion ( 3 ). The central core ( 2 ) is surrounded, in the lower portion thereof ( 3 ), by a circular projection ( 5 ) including side surfaces ( 9 ) and is capable of abutting, by means of at least one of the side surfaces ( 9 ), at least one of the side surfaces of a circular projection of an adjacent block.

The present invention relates to an armor layer of a protectivestructure for sea and/or river construction work against waves andcurrents comprising a plurality of artificial blocks.

Among the different components that make up a protective structure forsea and/or river construction work, the armor layer is the key elementfor ensuring the stability of the structure and is the main protectiveelement in the structure against swells. The armor layer can be made ofnatural riprap or artificial blocks, usually made of concrete.

Numerous studies have been carried out to develop effective artificialblocks, with a view primarily to proposing optimized shapes resulting inhigh robustness, as well as high hydraulic stability, thereby reducingthe amount of concrete required and consequently costs. However, it isgenerally recognized that increased robustness results in reducedstability, and vice versa.

Stability depends on the ability of the blocks not only to engage withthe slopes beneath the construction work to be protected, but also andprimarily to be assembled together using the specific form of theblocks, forming a protective armor layer that leaves sufficient emptyspaces to absorb the hydraulic energy to which the construction work issubjected.

Robustness is the mechanical strength of the blocks against shocks,stresses and erosion, provided by the shape of the blocks. This shapealso determines the interconnection properties of the blocks and thevoid ratio of the armor layer. This ratio must be high enough todisperse the energy of the waves and to reduce the action of upliftpressure.

In particular, the armor layer may settle over time and under theeffects of the stresses caused by the swell and the current, and theblocks may begin to oscillate between two positions, which acceleratesdegradation of the armor layer.

Blocks that have a slender shape improve the individual stability of theelements and resistance against overtopping. However, such blocksprovide low structural strength, which may lead to rapid degradation ofthe armor layer.

Blocks that have a less slender shape, i.e. larger blocks, withprotuberances intended to increase interconnection with adjacentelements, generally provide high hydraulic performance. However, toguarantee the stability of the structure, such blocks usually have to belaid according to stringent layout rules, which makes the armor layertime-consuming and difficult to build. Such difficulty notably resultsin a relative variability in the performance of these blocks.

It is also known to use blocks with a square core and pointedprotuberances at each corner, and a protuberance on each face of thesquare. However, these protuberances are fragile parts that aresusceptible to damage, notably because they are points of contact orsupport between adjacent blocks.

One objective of the invention is to improve the performance of aprotective structure, notably in terms of dissipation of swell energy,using blocks providing high structural strength that can be laid in anarrangement that is easy to build and provides uniform porosity.

For this purpose and according to a first aspect, an armor layer of aprotective structure for sea and/or river construction work comprising aplurality of protective blocks is proposed. Each protective block has acentral core having an upper portion and a lower portion. The lowerportion of the central core is surrounded by a circular protuberancehaving lateral faces that is able to butt, via at least one of thelateral faces, against at least one of the lateral faces of a circularprotuberance of an adjacent block.

The presence of the circular protuberance enables the blocks to bearranged easily together, notably making it possible to include aminimum distance between the central cores of two adjacent blocks, aswell as making it easy to partially pave the underlying surface of theslope, making it possible to protect same and to encourage the flow ofwater over the top. Furthermore, the upper portion of the central coremakes it possible to absorb a portion of the energy of the swell,encouraging dispersion of the water when the swell hits the block. Theupper portion of the central core therefore acts as a dissipationelement and the upper portions of the different blocks provide the armorlayer with a rough envelope that limits the amplitude of the movementsof the swell on the armor layer, in particular due to the spaces createdabout the upper portions of the cores by the circular protuberances.With an orderly or random layout plan, it is easy to obtain a uniformdistribution of the blocks and of the upper portions of the blocks, anda uniform porosity in the armor layer. Furthermore, the shape of thecircular protuberances permits arrangements having openings arrangedregularly between adjacent blocks, which facilitates transverse flowsthat increase the stability of the blocks.

Preferably, the circular protuberance can provide partial paving of asurface with adjacent protective blocks in contact with one another viaat least one of the adjacent surfaces of the circular protuberance. Thepartial paving may vary between 60% and 90% of the surface on which theblocks are laid, preferably between 70% and 85%.

The central core may have a lower base and an upper base, which arepreferably flat, the lower base and the upper base being square oroctagonal and joined by the lateral faces. The circular protuberance maybe arranged about the lower portion of the lateral faces of the core,from the lower base of the central core.

The core is preferably a square- or octagonal-based right prism.

The circular protuberance may have an octagonal lateral contour. Thecircular protuberance may have a square lateral contour having a notchon at least one of the sides, the notch being able to cooperate with avertex of the square lateral contour of a protuberance of an adjacentblock. Thus, in the case of an octagonal lateral contour, adjacentblocks are in contact with one another by at least one of the lateralfaces of the protuberance. In the case of a square lateral contour,adjacent blocks are in contact via the vertexes of the contour and thenotches of the sides of the contour. In both cases, the contact surfacesimprove the stability of the blocks between one another, and thegeometry of the circular protuberance makes it easy to position theblocks in relation to one another.

The octagonal lateral contour may be a square lateral contour in whichthe vertexes are chamfered. In this case, the lateral contour is not aregular octagon, but every other lateral face has a smaller surface.

Preferably, the circular protuberance forms, with the lower base of thecore, a preferably flat lower surface of the block. Said lower surfaceof the block is the surface on which the block rests on the underlyingslope.

Preferably, the circular protuberance also has a circular surface thatis inclined, for example to between 0° and 70° and preferably to between5° and 65°, joining the upper extremity of the lateral contour of thecircular protuberance to the lateral faces of the core. Such an inclinedsurface facilitates manufacture of the block, in particular by casting,and also makes it possible to obtain a more robust block.

The perimeter of the lateral contour of the circular protuberance maydiminish in the vicinity of the lower surface of the block 1.

The height of the circular protuberance may constitute between 25% and85%, preferably between 40% and 70%, of the total height of the block.The width, notably minimal, of the upper portion of the central core mayconstitute between 40% and 95%, preferably between 50% and 75%, of thetotal width of the block 1.

The circular protuberance may have vertical grooves on the lateral facesof same.

The protective block may have at least one vertical through-hole. It mayalso have at least one horizontal through-hole. These holes facilitatethe flow of water within the armor layer, in particular the flow ofwater towards the sea or the ocean.

According to a second aspect, a protective structure for sea and/orriver construction work comprising a plurality of blocks according tothe first aspect is proposed. The structure may include a centralelement, at least one filter layer and one armor layer comprising aplurality of blocks according to the first aspect.

Preferably, the blocks form partial paving covering between 60% and 90%,and preferably between 70% and 85%, of the surface on which the blocksare laid.

The invention is further described with reference to four specificembodiments provided by way of nonlimiting examples and illustrated inthe attached drawings, in which:

FIG. 1 is a three-dimensional view of a block according to a firstembodiment of the invention;

FIG. 2 is a top view of an armor layer formed by blocks according to thefirst embodiment;

FIG. 3 is a three-dimensional view of a block according to a secondembodiment of the invention;

FIG. 4 is a three-dimensional view of a block according to a thirdembodiment of the invention; and

FIG. 5 is a three-dimensional view of a block according to a fourthembodiment of the invention;

FIG. 1 shows a block 1 according to a first embodiment. In thisembodiment, the block 1, made for example of concrete, has a centralcore 2 with a lower portion 3 and an upper portion 4, and a circularprotuberance 5 arranged about the lower portion 3 of the central core 2.

The central core 2 has a lower base 6 (shown using a dotted line), anupper base 7 and lateral faces 8.

More specifically, the core 2 has two square bases 6, 7 forming the twomain surfaces, which are preferably flat, that are joined by fourlateral faces 8. The lateral faces 8 are free at the upper portion ofsame and covered by the circular protuberance 5 at the lower portion ofsame.

In the present case, the square bases, i.e. the bases 6 and 7, areconsidered to be identical and parallel. Furthermore, the lateral faces8 are considered to be perpendicular to said bases 6, 7. Thus, thecentral core 2 of the block 1 is a square-based right prism.

The circular protuberance 5 has an octagonal lateral contour. Inparticular, the circular protuberance 5 has eight lateral faces 9. Theoctagonal contour of the circular protuberance 5 may be regular, i.e.have eight equal lateral faces 9, or irregular as shown in FIG. 1. Inthe latter case, the lateral faces 9 of the octagonal contour areidentical pairs. More specifically, successive lateral faces of thecircular protuberance 5 may have successive surfaces having twodifferent values. Such an octagonal contour may in particular beobtained by chamfering the vertexes of the initial square contour. Thelateral faces resulting from the edges of the square have the samesurface area, which is greater than the surface area of the lateralfaces formed by the chamfers. The lateral faces of the circularprotuberance 5 then have equal pairs of surface areas.

The circular protuberance 5 may also have a circular surface 10 joiningthe lateral faces 9 of the circular protuberance 5 to the lateral faces8 of the upper portion 4 of the central core 2. The circular surface 10may thus have several faces 11 having angles from the horizontal ofbetween 0° (in this case, the circular surface 10 is a shoulder) and70°, for example between 5° and 65°.

In FIG. 1, the circular surface 10 has eight faces 11, each face 11joining a lateral face 9 of the circular protuberance 5 to the upperportion 4 of the central core 2.

The lower portion of the circular protuberance 5 forms, with the lowerbase 6 of the central core 2, a preferably flat lower surface 12 of theblock 1.

Advantageously, the lateral faces 9 of the circular protuberance 5 maybe perpendicular to the bases 6, 7 of the central core 2. Alternatively,the lateral faces 9 of the circular protuberance 5 may be inclined, inthe vicinity of the lower surface 12 of the block 1, towards the insideof the block in order to facilitate the flow of water between theblocks. In other words, the perimeter of the lateral contour of thecircular protuberance 5 may diminish in the vicinity of the lowersurface 12 of the block 1.

The height of the circular protuberance 5 constitutes 65% of the totalheight of the block 1, 50% of which corresponds to the lateral faces 9.The width, notably minimal, of the upper portion 4 of the central core 2constitute 60% of the total width of the block 1. Each chamfer forming alateral face 9 corresponds to the removal of 20% of the total width ofthe block 1.

FIG. 2 shows an armor layer 13 of a protective structure. The armorlayer 13 comprises several blocks 1 (thirteen of which are shown in FIG.2). The blocks 1 are arranged to butt up against one another. Inparticular, the lateral faces 9 of the circular protuberance 5corresponding to the chamfers are arranged to butt up against thelateral faces 9 of the adjacent blocks. This makes it easy to arrangethe different blocks 1 in the armor layer to obtain the desired spacingbetween the different blocks.

FIG. 3 shows a second embodiment of a protective block 1. The referencesigns used in FIG. 3 are the same as those used for the firstembodiment, and they refer to the same elements.

In FIG. 3, the circular surface 10 only has four faces 11, the lateralfaces 9 of the circular protuberance 5 formed by the chamfers beingtaller than the other lateral faces.

FIG. 4 shows a third embodiment of a protective block 1. The referencesigns used in FIG. 4 are the same as those used for the firstembodiment, and they refer to the same elements.

In FIG. 4, the central core 2 has a lower base and an upper base 7 thatare regular octagons. The upper portion 4 of the central core 2therefore has eight identical lateral faces 8. Furthermore, the circularprotuberance 5 also has a regular octagonal lateral contour, such thatthe upper portion 4 is a homothetic transformation of the circularprotuberance 5. The inclined surface 10 also has eight identical faces11.

According to this third embodiment, adjacent blocks 1 butt against thelateral faces 9. Since the eight lateral faces 9 of the circularprotuberance 5 are identical, the blocks can be arranged more easily,with fewer orientation constraints.

FIG. 5 shows a fourth embodiment of a protective block 1. The referencesigns used in FIG. 5 are the same as those used for the firstembodiment, and they refer to the same elements.

In FIG. 5, the block 1 has a circular protuberance 5 with a squarelateral contour. The circular protuberance 5 therefore has fouridentical lateral faces 9, and the vertexes of the lateral faces are notchamfered. However, the circular protuberance 5 has notches 14 tofacilitate arrangement of the blocks together. The notches 14 are in themiddle of the lateral faces 9. The notches 14 enable cooperation withthe vertexes of the circular protuberance of the adjacent blocks, andform openings between the circular protuberances of adjacent blocks. Inthe case shown in FIG. 5, the notches 14 expose a fraction of the lowerportion of the central core 2.

In each of the embodiments described above, the perimeter of the lateralcontour of the circular protuberance 5 may diminish in the vicinity ofthe lower surface 12 of the block 1.

The circular protuberance may have vertical grooves on the lateral facesof same. Furthermore, the protective block 1 may also have at least onevertical through-hole and/or at least one horizontal through-hole tofacilitate the flow of water in the armor layer.

A protective structure incorporating such an armor layer may alsoconventionally include a filter layer beneath the armor layer and a corecarrying the filter layer and the armor layer and providing an overallshape to the assembly.

1. An armor layer of a protective structure for sea and/or riverconstruction work comprising several protective blocks (1), each blockhaving a central core (2) with an upper portion (4) and a lower portion(3), characterized in that the lower portion (3) of the central core (2)is surrounded by a circular protuberance (5) with lateral faces (9) andin that at least one of the lateral faces (9) can butt against at leastone of the lateral faces of a circular protuberance of an adjacentblock.
 2. The armor layer as claimed in claim 1, characterized in thatthe circular protuberance (5) of each block can provide partial pavingof a surface with adjacent protective blocks (1) in contact with oneanother via at least one of the adjacent faces of the circularprotuberance (5).
 3. The armor layer as claimed in claim 1,characterized in that the central core (2) of each block has a lowerbase (6) and an upper base (7), that are preferably flat, the lower base(6) and the upper base (7) being square or octagonal and joined by thelateral faces (8), and in that the circular protuberance (5) is arrangedabout the lower portion of the lateral faces (8) of the central core(2), from the lower base (6) of the central core (2).
 4. The armor layeras claimed in claim 1, characterized in that the central core (2) ofeach block is a square- or octagonal-based right prism.
 5. The armorlayer as claimed in claim 1, characterized in that the circularprotuberance (5) of each block includes an octagonal lateral contour ora square lateral contour having a notch (14) on at least one of thesides of same, the notch (14) being able to cooperate with a vertex ofthe square lateral contour of a circular protuberance of an adjacentblock.
 6. The armor layer as claimed in claim 5, characterized in thatthe octagonal lateral contour of the circular protuberance of each blockcorresponds to a square lateral contour in which the vertexes arechamfered.
 7. The armor layer as claimed in claim 1, characterized inthat the circular protuberance (5) of each block forms, with the lowerbase (6) of the core, a preferably flat lower surface (12) of the block(1).
 8. The armor layer as claimed in claim 1, characterized in that thecircular protuberance (5) of each block also has an inclined circularsurface (10) joining the upper extremity of the lateral contour of thecircular protuberance (5) to the lateral faces (8) of the central core(2).
 9. The armor layer as claimed in claim 1, characterized in that theblocks (1) form partial paving covering between 60% and 90% of thesurface on which the blocks are laid.
 10. A protective block designed tobe incorporated into an armor layer of a protective structure for seaand/or river construction work as claimed in claim 1.